Compound Interest Calculator
Estimate compound interest growth with principal, rate, time, and compounding frequency.
- Free
- No sign-up
- Runs in your browser
Start from an example
Interest is added
Effective yearly return: 10%. Most bank FDs add interest quarterly.
Maturity value
₹2,59,374
after 10 years at 10% a year, compounded yearly
- Total invested₹1,00,000 (39%)
- Interest earned₹1,59,374 (61%)
- Total invested
- ₹1,00,000
- Interest earned
- ₹1,59,374
- Effective yearly return
- 10%
- Maturity value
- ₹2,59,374
Your money grows 2.6× — interest makes up 61% of the final amount. Staying invested longer makes compounding work much harder.
How your money grows, year by year
- Money you put in
- Interest earned
The interest part grows faster each year because interest earns interest.
Year-by-year breakdown
| Year | Invested | Interest | Balance |
|---|---|---|---|
| 1 | ₹1,00,000₹1L | ₹10,000₹10K | ₹1,10,000₹1.1L |
| 2 | ₹1,00,000₹1L | ₹21,000₹21K | ₹1,21,000₹1.21L |
| 3 | ₹1,00,000₹1L | ₹33,100₹33.1K | ₹1,33,100₹1.33L |
| 4 | ₹1,00,000₹1L | ₹46,410₹46.4K | ₹1,46,410₹1.46L |
| 5 | ₹1,00,000₹1L | ₹61,051₹61.1K | ₹1,61,051₹1.61L |
| 6 | ₹1,00,000₹1L | ₹77,156₹77.2K | ₹1,77,156₹1.77L |
| 7 | ₹1,00,000₹1L | ₹94,872₹94.9K | ₹1,94,872₹1.95L |
| 8 | ₹1,00,000₹1L | ₹1,14,359₹1.14L | ₹2,14,359₹2.14L |
| 9 | ₹1,00,000₹1L | ₹1,35,795₹1.36L | ₹2,35,795₹2.36L |
| 10 | ₹1,00,000₹1L | ₹1,59,374₹1.59L | ₹2,59,374₹2.59L |
Complete Guide to Compound Interest Calculator
Compound interest is the process where interest earned on an investment is reinvested to generate additional interest over time. Unlike simple interest, which is calculated only on the principal, compound interest accelerates wealth creation exponentially. Our Compound Interest Calculator allows you to simulate different scenarios – principal amount, interest rate, tenure, compounding frequency, and monthly contributions – to see the magic of compounding in action.
In this comprehensive guide, we’ll explore the mathematics of compound interest, its applications in savings accounts, fixed deposits, mutual funds, and loans. We’ll compare different compounding frequencies, discuss the Rule of 72, and answer frequently asked questions about compounding.
1. What is Compound Interest?
Compound interest is interest calculated on the initial principal plus all accumulated interest from previous periods. It’s often called “interest on interest.” For example, ₹1,00,000 at 10% per annum compounded annually becomes ₹1,10,000 after year 1, ₹1,21,000 after year 2, and ₹1,33,100 after year 3. The growth accelerates because each year’s interest earns interest in subsequent years.
2. Compound Interest Formula
A = P (1 + r/n)^(nt)
Where:
A = Final amount
P = Principal (initial investment)
r = Annual interest rate (in decimal)
n = Number of times interest compounds per year
t = Number of years
With monthly contributions: A = P(1+r/n)^(nt) + PMT × [((1+r/n)^(nt) - 1) / (r/n)]
Our calculator handles both scenarios.
3. How to Use This Calculator
- Enter the principal amount you want to invest.
- Set the annual interest rate (e.g., FD 7%, equity 12%, debt 8%).
- Choose the investment tenure in years.
- Select compounding frequency (yearly, half-yearly, quarterly, monthly). Higher frequency yields more.
- Optionally add a monthly contribution (added at the start of each month) to simulate a SIP or recurring deposit. It grows at the compounding frequency you choose.
- View total invested, total interest, maturity value, and year-by-year growth.
- Check the year-by-year chart showing how much is your money and how much is interest.
- Download the report as a CSV (opens in Excel) or copy a link to share your numbers.
4. Effect of Compounding Frequency
- Yearly compounding: Effective rate = 10.00%
- Half-yearly: (1 + 0.10/2)^2 - 1 = 10.25%
- Quarterly: (1 + 0.10/4)^4 - 1 = 10.38%
- Monthly: (1 + 0.10/12)^12 - 1 = 10.47%
- Daily: ~10.52%
5. The Rule of 72
The Rule of 72 is a quick way to estimate how long it takes for an investment to double. Divide 72 by the annual interest rate. For example, at 12% CAGR, money doubles in 72/12 = 6 years. At 8%, it takes 9 years. This rule works well for rates between 6-15%. Use our calculator to verify.
6. Real-World Applications
- Savings Account: Interest compounded quarterly or monthly.
- Fixed Deposits (FD): Usually quarterly compounding.
- Recurring Deposits (RD): Monthly deposits, quarterly compounding.
- Mutual Funds: Compounding through NAV growth (no fixed rate, but calculator helps estimate).
- Loans (Credit Card, Personal): Compound interest works against you – pay early!
7. Power of Starting Early
Compare two investors: Investor A starts at age 25, invests ₹50,000 annually for 10 years (total ₹5 lakhs), then stops. Investor B starts at age 35, invests ₹50,000 annually for 30 years (total ₹15 lakhs). Assuming 12% CAGR, at age 65:
Investor A: ₹50,000 × [((1.12)^10 - 1)/0.12] × (1.12)^30 = ~₹2.5 crores
Investor B: ₹50,000 × [((1.12)^30 - 1)/0.12] = ~₹1.2 crores
Starting early matters more than investing more. Use our calculator to see for yourself.
8. Frequently Asked Questions (FAQ)
Simple interest is calculated only on principal. Compound interest is calculated on principal + accumulated interest, leading to exponential growth.
Adding regular contributions significantly boosts returns, especially over long periods. Our calculator shows the combined effect.
For savings and investments, yes. For loans (credit cards), compound interest is detrimental – pay off quickly.
Yes, set monthly contribution as your SIP amount, and expected annual return as the rate. Our SIP calculator is more precise for varying returns.
It uses exact financial formulas. Results are mathematically accurate for given inputs.
For safe instruments (FD): 7-9%. For equity: 12-15% historical. For aggressive goals: 15-18% possible but higher risk.
Click “Download report (Excel/CSV)”. The file includes your inputs, the results and the year-by-year table. Use “Copy link” to share these exact numbers.
More frequent compounding means interest is added to principal sooner, so subsequent interest calculations include more base amount.
9. Examples of Compound Interest in Action
Example 1 – FD: ₹5,00,000 at 7% compounded quarterly for 5 years. Quarterly rate = 1.75%, periods = 20. Final = 5L × (1.0175)^20 = ₹7,08,000 approx.
Example 2 – SIP with compounding: ₹10,000 monthly at 12% annual (1% monthly) for 15 years. Use monthly contribution mode. Final ≈ ₹50,00,000.
Example 3 – Loan EMI (reverse): Compound interest works against you. A ₹10,00,000 personal loan at 15% compounded monthly for 5 years results in total payment ~₹14,27,000.
10. Advanced Strategies to Maximize Compounding
- Start as early as possible – even small amounts grow massively over decades.
- Choose investments with higher compounding frequency (monthly > quarterly > yearly).
- Reinvest all dividends and interest (avoid payout options).
- Add regular contributions (SIP, RD) to accelerate growth.
- Avoid premature withdrawals – breaking compounding resets progress.
11. Final Thoughts
Compound interest is the most powerful force in finance. Whether you’re saving for retirement, a child’s education, or a dream home, understanding and harnessing compounding can turn modest savings into substantial wealth. Our Compound Interest Calculator empowers you to experiment with different scenarios and see the long-term impact.
Start using the Compound Interest Calculator above now. Input your numbers, adjust monthly contributions, and watch your money grow. Remember – time is your greatest ally in compounding.